Honestly I really really want to agree with you. Problem is, having Hyung be happy means either he's alone (yeah why doesn't he just get fucked over with the I don't need anyone happiness) or another person coming in, to take the place of subin. The thing about the second option is that the character replacing subin wont be easy to like, unless he's made a main character. Also if that happened, it would kind of be like "oh ok Hyung listen so sorry but since hyunwoo is more important than you and therefore should end up with subin, we're just gonna make up another person for you bc u know, we're fair and all"
I wouldn't mind the second option myself. Most of the time I end up preferring the new love interest over the mc. In this case I would easily prefer a new guy over Subin. I don't hate him but he's not my favorite type of char I'll leave it at that.
Everyone can go hate on me but imho I prefer subin to end up with hyunwoo. Both hyunwoo and subin are so fucked up, they need help. The idea of subin ended up with hyung just doesn't work out for me. Kang Jun is one precious being, he deserves someone better than subin